1. Technical Field
The present invention relates to a progressive-power lens and a progressive-power lens design method.
2. Related Art
International Publication WO97/19382 describes a progressive multifocal lens used as a spectacle lens suitable for presbyopia correction or other vision correction and having a progressive-power surface provided on the eyeball-side surface instead of the object-side surface as in related art. This configuration allows the object-side surface to be a spherical surface having a fixed base curve, whereby no variation in magnification caused by the shape factor will occur, and the difference in magnification between the distance portion and the near portion can be reduced. In addition, any change in magnification of the progression portion can be suppressed. As a result, the amount of image shaking and distortion due to the difference in magnification can be reduced, whereby a progressive multifocal lens that provides a comfortable field of view can be provided. International Publication WO97/19382 also describes that a combination method allows a progressive-power surface and a toric surface for astigmatism correction to be combined on the eyeball-side surface to reduce the amounts of image shaking and distortion in a progressive multifocal lens for astigmatism correction.
Although the technology described in International. Publication WO97/19382 and other technologies have improved the performance of a progressive-power lens, some users still cannot adapt to the characteristics of a progressive-power lens, particularly the image shaking phenomenon, and further improvement is therefore desired.